The following abbreviations are herewith defined, at least some of which are referred to within the following description of the present invention.
3GPP Third Generation Partnership Project
AGCH Access Grant Channel
EC Emulated Core
EPC Enhanced Power Control
FDD Frequency Division Duplex
GTP GPRS Tunneling Protocol
HLR Home Location Register
HOP Higher Order Provisioning
HSPA High Speed Packet Access
HSS Home Subscriber Register
IE Information Element
IMS IP Multi-Media Subsystem
IMT International Mobile Telecommunication
LTE Long Term Evolution
MAC Medium Access Control
MBB Mobile Broadband
MBH Mobile Backhaul
MM Mobility Management
MME Mobility Management Entity
MPLS Multi-Protocol Lable Switching
MVNO Mobile Virtual Network Operator
MW Microwave
NAS Non-Access Stratum
NG Next Generation
NGMN Next Generation Mobile Networks
NLOS Non/Near Line of Sight
OSS Operations Support System
PDCP Packet Data Convergence Protocol
PDU Protocol Data Unit
QoS Quality of Service
RA Radio Access
RAN Radio Access Network
RBS Radio Base Station
RLC Radio Link Control
RRC Radio Resource Control
S1AP S1 Application Protocol
SCBH Small Cell Backhaul
SCTP Stream Control Transmission Protocol
SGw Service Gateway
SON Self-Organized Networking
TDD Time Division Duplex
UE User Entity/Equipment (Mobile Terminal)
UDP User Datagram Protocol
USIM User Subscriber Identity Module
In the telecommunications field, small cell backhaul is playing a critical role in mobile broadband, and is rising in importance on account of the introduction of heterogeneous networks, sometimes referred to as hetnets. Basically, the small cell backhaul involves the deployment of numerous small cell radio base stations which complement the macrocell radio base stations. The deployment of small cell radio base stations requires a highly scalable and flexible small cell backhaul solution. The predominant approach used today to implement the small cell backhauling solution is to scale down the existing macro cell backhauling solution.
Referring to FIG. 1 (PRIOR ART), there is a diagram of an exemplary wireless communication system 100 which shows the basic features of this predominant approach to implementing the small cell backhauling solution. In this approach, the small RBSs 102 are connected via a MBH network 104 to the 3GPP core 106. The MBH connectivity is normally pre-configured between the small RBSs 102 and the 3GPP core 106 utilizing an OSS 108 or some other network management solution. This MBH connectivity forms the basis over which Mobile Broadband (MBB) connectivity to the mobile terminals 110, over 3GPP air interfaces 112, can be set up dynamically.
In this approach, the 3GPP core 106 cooperates with the small RBSs 102 to establish 3GPP bearers 114 through which MBB data can flow between the mobile terminals 110 and e.g. the Internet 114. Portions of these 3GPP bearers 114 run through MBH connections 116, typically as tunnels across a packet network (e.g. GTP tunnels across an MPLS based network). In this situation, one can already observe a difference in control mechanisms of connectivity between the traditional MBH domain and the 3GPP domain:                The MBH connections 116 are semi-static and controlled by the OSS 108.        The 3GPP bearers 114 are dynamic and established by the 3GPP core 106 and the small RBSs 102 whenever 3GPP mobile terminals 110 request MBB resources.        
As a result of this difference, there is an increasing interest in “pushing” the MBH connections 116 in a more dynamic on-demand direction, i.e. towards an approach that bears more resemblance to the MBB connectivity than to the traditional MBH connectivity. To this end, the operators and system vendors are looking at an alternative small cell backhaul solution which is described next with respect to FIG. 2 (PRIOR ART).
Referring to FIG. 2 (PRIOR ART), there is a diagram of an exemplary wireless communication system 200 which shows the basic features of this alternative small cell backhaul solution. In this approach, a first MBH backhaul link 202 between the small RBSs 204 and the rest of the MBH network 206 (MBH cloud 206) is provided by a LTE TDD wireless link 208, in particular one supporting a hub-and-spoke structure. The LTE TDD wireless link 208 has spokes which end at the small RBSs 204. The LTE TDD wireless link 208 has a hub which ends at a LTE TDD RBS 210. Typically, the LTE TDD RBS 210 uses the LTE TDD wireless link 208 in the form of a NLOS point-to-multipoint radio link 208 to connect with the small RBSs 204. The small RBSs 204 provide LTE FDD links 212 to their respective mobile stations 214 (UEs 214).
The use of “LTE” in the backhaul, e.g. LTE TDD 208 as in this example, means that the establishment of this connectivity must be secured, and this requires an LTE (3GPP) core. In the current solutions pursued in various trials and announcements, this LTE 3GPP core 216 is emulated in the node type previously referred to herein as the LTE TDD RBS 210. Plus, the first MBH backhaul link 202 (e.g., LTE TDD backhaul hop 202) can be implemented by placing a LTE TDD UE equivalent 218 on each of the original LTE FDD RBSs 204, which then cooperate with the LTE TDD RBS 210 and in particular the emulated LTE 3GPP core entity 216 (e.g., emulated core 216) to establish the first MBH backhaul link 202. A step-by-step discussion is provided next to explain how the connectivity between the mobile stations 214 and the 3GPP core 222 can be established per this small cell backhaul solution. The steps are as follows:                1. The MBH OSS 220 establishes connectivity between the 3GPP core 222 and the LTE TDD RBS 210.        2. The LTE TDD RBS's emulated core 216 provides the necessary 3GPP core functions so that the LTE TDD wireless link 208 is established between the LTE TDD RBS 210 and the small RBSs 204. Now, the small RBSs 204 have full MBH connectivity to the 3GPP core 222.                    a. The MBH connectivity for the small RBSs 204's cells therefore is the combination of MBH 224 and the LTE TDD wireless link 208.                        3. The small RBSs 204 now utilizes 3GPP signaling to interface with the 3GPP core 222 and establish the 3GPP radio bearers 226 for MBB services to their respective mobile stations 214.        
Referring to FIG. 3 (PRIOR ART), there is a diagram of an exemplary wireless communication system 300 which shows the basic features of yet another alternative small cell backhaul solution which has a set-up similar to FIG. 2's solution except that the LTE TDD RBS 210 no longer has the emulated core 216 located therein but instead there is a separate 3GPP core 302 (shown as 3GPP core 2) which is located in the MBH network 206 (MBH cloud 206). This particular solution is discussed in 3GPP TR 36.806 “Relay Architectures for E-UTRA (LTE-Advanced)” V.9.0.0, March 2010 (the contents of which are incorporated by reference herein). A step-by-step discussion is provided next to explain how the connectivity between the mobile stations 214 and the 3GPP core 222 can be established per this small cell backhaul solution.                1. The OSS 220 establishes the MBH connection 304 (“MBH 1”) between the 3GPP cores 222 and 302.        2. The OSS 220 also establishes another leg 306 (“MBH 2”) of the MBH connection between the 3GPP core 302 and the LTE TDD RBS 210.        3. The 3GPP core 302 is used to control small cell backhaul bearers 308 (“3GPP Relay Bearers”) and establish the connection to the small RBSs 204.                    a. The MBH connection of the small RBSs 204 is therefore the combination of small cell backhaul bearers 308 (partly carried over MBH 2) and MBH 1.                        4. The small RBSs 204 now have connectivity all the way to the 3GPP core 222 to establish 3GPP bearers 310 for MBB services to their respective mobile stations 214.        
Although these small cell backhaul solutions work well in most applications there is still a desire to improve upon them to provide a more flexible small cell backhaul solution. One such new and improved small cell backhaul solution is the subject of the present invention.